tirsdag 11. januar 2022

Air pollution: Delhi's smog problem is rooted in India's water crisis

Every winter, Indian capital Delhi's toxic air is fuelled by farmers burning crop stubble. But the fires don't stop. Why? The answer lies in water, writes climate expert Mridula Ramesh. India loses an estimated $95bn (£70bn) to air pollution every year. From mid-March to mid-October, when Delhi's air quality varies from good to moderate to unhealthy for sensitive groups, chatter on air pollution and its causes is muted.

But then comes winter. Pollution in any city mixes vertically in the atmosphere, and the height at which this happens shrinks by more than half in the winter, raising the concentration of pollution. Two new sources also enter the mix. By the end of October, when the rains have ceased, the winds begin to blow in from the northwest, carrying fumes from burning fields. Then there is the Diwali, the popular festival lights, where millions burst fire crackers to celebrate.